In the manufacture of decorative concrete blocks for retaining walls and like uses, it is customary to achieve a weathered and aged look by tumbling the cured blocks in a drum or similar tumbling apparatus to cause blocks to collide and damage their edges. This process is labor intensive and time consuming because the cured blocks must be loaded into the tumbling apparatus and then removed therefrom. In addition, some wastage of finished products occurs because of the impacts of blocks upon each other. Since blocks of this type are frequently molded in three-piece sets, when one piece of a set of three is damaged, the set is incomplete and palleting of the sets is delayed and obstructed.